Landing gear is known comprising a leg hinge-mounted to the structure of the aircraft so as to be movable between a deployed position and a retracted position. The leg is stabilized in the deployed position by at least one main brace comprising two links that are hinged together, one of the links being coupled to the leg and the other link being coupled to the structure of the aircraft. When the landing gear is in the deployed position, the two links of the main brace are held in a substantially aligned position by a locking device.
The locking device itself comprises a set of two links that are hinged together, one of the links being coupled to the main brace, while the other link is coupled either to the leg or to the structure of the aircraft. The two links are in a substantially aligned position when the landing gear is in the deployed position. The term “secondary alignment” is used to mean the alignment of the links of the locking device, as contrasted to the main alignment of the links of the main brace. That is why the locking device is also referred to as a secondary brace. The secondary alignment is generally maintained by springs that confirm the links in abutment one against the other when in the aligned position.
A single-acting unlocking actuator is coupled to one of the links in order to break the secondary alignment against the springs when it is desired to retract the landing gear.
It is known to provide a raising linkage in which the links of the secondary brace become realigned when the landing gear reaches the retracted position. The secondary brace, together with that one of the links of the brace that is hinged to the aircraft, then forms a rigid structure to which the leg of the landing gear is connected by the other link of the brace, thereby enabling the landing gear to be locked in the retracted position, and thus avoiding the need to use an uplock box for the landing gear. Nevertheless, in such a configuration, care must be taken to ensure that the action of the unlocking actuator is stopped before the links of the secondary brace are realigned, since otherwise the actuator would prevent any realignment. This requires sequencing to be used, and should that fail the landing gear would be prevented from locking in the retracted position.